When the new Twins ballpark was sited next to Hennepin County's garbage burner in downtown Minneapolis, county officials assured state legislators that there wouldn't be any odor problem despite the proximity to a building that takes in 1,000 tons of garbage a day. Now the county is considering spending an estimated $2.3 million to remodel the building and grounds, about $500,000 of that to deal with odor control.

Two of the county commissioners who attended a briefing on the plans Thursday were not happy to learn that changes to the burner are needed because of the ballpark.

Jeff Johnson, a former state legislator, remembered being told years ago at the

State Capitol that smells would not be a problem for the ballpark. Gail Dorfman also recalled that the county's own study had determined that the stadium would not be affected by odors or pollution from the trash burner.

"We were told there was nothing to mitigate," she said. "Why all of a sudden is there something to mitigate?"

The answer, they were told, is that the ballpark is being built nearer the Hennepin Energy Recovery Center than originally planned. The burner will be behind the backs of fans on the stadium's northwest side. But a wide, elevated sidewalk called the promenade that rings part of the stadium will be 32 feet off the ground and within about 100 feet of the garbage burner's east side, where trucks now exit the building after dumping their garbage inside.

When stadium construction crews worked in the promenade area on hot days last summer, they reported odors coming from the burner when the exit doors were open, said Dan Kenney, executive director of the Minnesota Ballpark Authority. Kenney said his view is that the stadium and housing that's beginning to develop in the area makes the burner a "completely different animal" from when it was built more than 20 years ago in an industrial area of railroad tracks and parking lots.

"There weren't generally smells at parking lot level," Kenney said. "Now we have a new elevated sidewalk that will be open 365 days a year ...

"There were no residents down there, but now we have more walkers, new transit and new development."

Any smells linked to the burner are coming not from its emissions but from trucks entering the plant, from wet garbage that leaks from the trucks onto surrounding pavement, and from the air that escapes from inside the plant when the doors open to let trucks in and out, said Commissioner Mike Opat.

To stop leaking odors, a "sally port" would be added at the truck entry. Trucks would drive into a room where the exterior door would close behind them before a second door opens to let them into the dumping area, effectively creating an air lock. The two truck exits that now face the stadium would no longer be used, replaced by a single new exit on the burner's north side. Door openings would be synchronized so entry and exit doors would not be open at the same time to prevent a flow-through of air and odors.

The county also has installed "spritzers" above doors for trucks. Carl Michaud, the county's director of environmental services, said the plan is to spray the equivalent of truck "perfume" on departing vehicles to kill the stench that often lingers in garbage haulers.

The cost of changes to mitigate odors adds up to about one-quarter of the $2.3 million that would be spent on the site. The rest would go for retaining walls, landscaping and tree plantings that would mask the burner's exterior, making it fit better with surroundings that are increasingly residential. Thousands of people are expected to walk or ride by the burner because that corner of the stadium will become a hub for passenger rail lines as well as the Cedar Lake bike trail.

"We have to decide to what extent we want to be a good neighbor in a changing neighborhood," said Commissioner Peter McLaughlin.

Dorfman agreed that aesthetic changes are necessary, but she said she was less certain that odors need to be fixed. Commissioner Jan Callison, who is new to the board, said she was "not on board yet" with the project and would like to tour the facility.

Architects will come back to the board with a firmer cost estimate and more detailed plans. Michaud said construction needs to begin in May to finish the job by the time the ballpark opens in spring 2010.

The burner operates from 4 a.m. to 10 p.m. on weekdays, on Saturdays from 6 a.m. to 6 p.m. and on Sundays from 6 a.m. to noon. Michaud said the facility may experiment with different schedules this summer to see how they work. Some haulers may want to avoid the burner on game days because of the traffic, he said.